Facebook confirmed Thursday in a blog post, prompted by a report by cybersecurity reporter Brian Krebs, that it stored “hundreds of millions” of account passwords in plaintext for years.
The discovery was made in January, said Facebook’s Pedro Canahuati, as part of a routine security review. None of the passwords were visible to anyone outside Facebook, he said. Facebook admitted the security lapse months later, after Krebs said logs were accessible to some 2,000 engineers and developers.
Krebs said the bug dated back to 2012.
“This caught our attention because our login systems are designed to mask passwords using techniques that make them unreadable,” said Canahuati. “We have found no evidence to date that anyone internally abused or improperly accessed them,” but did not say how the company made that conclusion.

According to Facebook - no breach or leak. Just an "ooops!" .... again.

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EDIT: That article is kinda wonky with it's formatting so here's a cleaner one if you're interested: